1. Field of the Invention
This invention relates to a resealable closure and, in particular, to a resealable closure particularly useful for plastic bags.
2. Brief Statement of the Prior Art
Plastic bags are used to preserve many items, such as food, mechanical items, electronic components and circuits, etc. In all of the applications it is desirable to have a resealable and reusable closure that will permit reuse of the plastic bag.
Mechanical closures have been developed in which a bead and a mating groove are formed on opposed edges of plastic bags, e.g, the ubiquous Baggies. Although the mechanical closures are fairly useful and will secure a plastic bag in most applications, the mechanical closures are not completely fluid-tight and leakage of fluids such as liquids and gases through the mechanical seal can occur. Consequently, some attempts have been made to provide an adhesive sealing closure, such as the adhesive closure shown in U.S. Pat. No. 3,307,773; and the heat or pressure bonded seal in U.S. Pat No. 3,717,533.
In U.S. Pat. Nos. 3,325,083 and 3,310,225, resealable closure are shown which utilize the self-adhesive property of some plastics particularly chlorinated polyolefins and polyvinyl chloride. In the former patent, the entire plastic container or bag is formed of self-adhesive polyvinyl chloride which is calendared in the areas which are to be non-adherent, leaving a small seal band at the top of the bag which is the uncalendered polyvinyl chloride.
A difficulty with this attempt is that it limits the useful materials and designs for the plastic bags. In U.S. Pat. No. 3,310,225, the self adhesive plastic is applied as a band along an external sealing flap of the plastic bag. The attempts of both of these patented inventions have a common disadvantage, which is that the seals are not effective against internal pressure and a fluid tight seal is thus difficult to achieve.
It is accordingly an objective of this invention to provide an economical closure for plastic bags and the like which is resealable, thereby permitting reuse of the plastic bags.
It is an additional object of this invention to provide a resealable closure for plastic bags which is fluid-resistant.
It is a further object of this invention to provide a closure for plastic bags which can withstand internal pressures within the bag while maintaining a fluid-tight seal.
It is also an objective of this invention to provide a resealable closure which is very economical and which can be fabricated without complex equipment. Other and related objectives will be apparent from the following description of the invention.